Klub tvrdí, že plán je jednoduchý.

In Czech, a subordinate clause introduced by že is normally separated by a comma.

So in Klub tvrdí, že plán je jednoduchý, the main clause is:

• Klub tvrdí = the club claims

and the subordinate clause is:

• že plán je jednoduchý = that the plan is simple

This comma is standard and much more obligatory than in English.

Že means that and introduces a content clause: what someone says, thinks, claims, knows, etc.

So:

• Klub tvrdí = the club claims
• že plán je jednoduchý = that the plan is simple

It works much like English that in The club claims that the plan is simple.

Tvrdí is the 3rd person singular present form of the verb tvrdit.

That matches klub, which is singular:

• já tvrdím = I claim
• ty tvrdíš = you claim
• on/ona/ono tvrdí = he/she/it claims

Since klub is grammatically singular, Czech uses tvrdí.

Also, tvrdit often means to claim, to assert, or to maintain, which is a bit stronger or more formal than just říkat = to say.

Czech has no articles, so there is no direct equivalent of a or the.

That means klub can mean:

• a club
• the club

The exact meaning depends on context. In your sentence, English happens to use the club, but Czech does not need a separate word for that.

Klub is in the nominative case, because it is the subject of the main clause.

In:

• Klub tvrdí = The club claims

klub is the thing doing the action, so nominative is the expected case.

Plán is also in the nominative case, because it is the subject of the subordinate clause.

Inside že plán je jednoduchý:

• plán = subject
• je = is
• jednoduchý = simple

So the structure is basically the plan is simple, and plán stays nominative.

Jednoduchý is an adjective agreeing with plán.

Since plán is:

• masculine
• singular
• nominative

the adjective must also be:

• masculine
• singular
• nominative

So you get:

• plán je jednoduchý

If the noun changed, the adjective would change too. For example:

• myšlenka je jednoduchá = the idea is simple
• řešení je jednoduché = the solution is simple

Yes. Je is the present tense of být = to be, and jednoduchý is simple.

So:

• plán je jednoduchý = the plan is simple

This is a very standard Czech sentence pattern: subject + je + adjective.

Klub is masculine inanimate.

That matters mainly for agreement patterns in adjectives, pronouns, and some past-tense forms. In this particular sentence, it does not visibly affect tvrdí, because present-tense verb forms in Czech do not show gender.

But it would matter elsewhere, for example in the past:

• Klub tvrdil... = The club claimed...

Yes, Czech word order is fairly flexible, but the neutral order here is:

• Klub tvrdí, že plán je jednoduchý.

You may also see other orders for emphasis, for example:

• Klub tvrdí, že jednoduchý je plán.

But that sounds marked and would emphasize a different part of the sentence. For learners, the original word order is the best default.

The í is a long i sound. So tvrdí has stress on the first syllable, like most Czech words, and the final vowel is held a bit longer.

Very roughly for an English speaker:

• tvrdí ≈ TVR-dee, but with a rolled or tapped Czech r

A tricky part is the cluster tvr-, since Czech allows consonant clusters that feel unusual to English speakers.

Že is pronounced roughly like zheh, where ž sounds like the s in measure or the g in beige.

So:

• že ≈ zheh

It is a very common Czech word, so it is worth getting comfortable with early.

Sometimes yes, depending on context, but claims is often better.

Compare:

• říká = says
• tvrdí = claims / asserts / maintains

Tvrdí can suggest that someone is stating something as true, sometimes with a slightly stronger, more insistent, or more doubtful nuance than plain říká.

So if the sentence is translated as The club claims that the plan is simple, that is a good match.

Because Czech does not need a dummy or repeated pronoun here. The noun plán is stated directly as the subject.

English also does this in the plan is simple. Czech simply says:

• plán je jednoduchý

No extra subject pronoun is needed.

It is in the present tense, but like English present tense, it can describe either:

• what the club is saying now
• a general current position or claim

So Klub tvrdí, že plán je jednoduchý can mean the club is currently making that claim, not just at this exact second.

Usually no, not in a standard sentence like this. Czech normally keeps že in this kind of clause.

English can say:

• The club claims the plan is simple

But Czech would normally still say:

• Klub tvrdí, že plán je jednoduchý.

So for learners, it is safest to include že.